To provide a quantified rotor type pump that gets rid of any weighty pulsation of discharge, and besides, there is not variation even if it is rotated by each optional angle.

A weighty pulsation of discharge comes forward when to three- lobe type rotors 1 and 2 are rotated at constant velocity. Accordingly, a pair of noncircular gears 7 and 8 are built in a driving part, and in time of a state that a fluid substance is discharged in bulk, each rotational speed rotors is made so as to be at a low speed, but in time of a state that it is discharged in a small quantity, a tooth profile form is determined so as to make it become at a high speed, thereby getting rid of any pulsation.